<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style type="text/css">
			.dark {
				background-color: black;
				color: white;
			}
		</style>
		<script src="js/jquery-3.7.1.min.js" type="text/javascript" charset="utf-8"></script>
		<script type="text/javascript">
			$(function() {
				let dark = false;
				$("button").click(function() {
					$(document.body).toggleClass("dark");
					if (dark == false) {
						$("button").addClass("dark");
						$("button").html("明亮模式");
						dark = true;
					} else {
						$("button").removeClass("dark");
						$("button").html("黑暗模式");
						dark = false;
					}
				})
			})
		</script>
	</head>
	<body>
		网页内容
		<button type="button" style="float:right;background-color: transparent;">黑暗模式</button>
	</body>
</html>
